1. Field of the Invention
The field of this invention is proteins which regulate cell function, and in particular, induce neural development or antagonize bone morphogenic proteins.
2. Background
Natural regulators of cellular growth, differentiation and function have provided important pharmaceuticals, clinical and laboratory tools, and targets for therapeutic intervention. A variety of such regulators have been shown to have profound effects on basic cellular differentiation and developmental pathways. For example, the recently cloned Xenopus cerberus protein induces the formation of head structures in anterior endoderm of vertebrate embryos. Similarly, the noggin protein induces head structures in vertebrate embryos, and can redirect mesodermal fates from ventral fates, such as blood and mesenchyme, to dorsal fates such as muscle and notochord and can redirect epidermal fates to anterior neural fates. The activities of chordin are similar to those of noggin, reflecting a common mechanism of actionxe2x80x94namely antagonizing bone morphogenic proteins (BMP) and thereby preventing their function. BMPs have diverse biological activities in different biological contexts, including the induction of cartilage, bone and connective tissue, and roles in kidney, tooth, gut, skin and hair development.
Different members of the TGFxcex2 superfamily can instruct cells to follow different fates, for example TGFxcex2 induces neural crest to form smooth muscle, while BMP2 induces the same cells to become neurons. In Xenopus experiments, dissociated animal cap cells (prospective ectoderm) become epidermis in response to BMP4 but become mesoderm in response to activin.
Since the sequence identity between activin and BMP4 is low, it is not surprising that they induce different fates. It is more surprising that members of the BMP subfamily, which are quite closely related in sequence, can induce distinct fates. A striking example results from implantation of a matrix impregnated with a BMP into muscle; when the effects are monitored histologically, BMP2, 4 and 7 induce endochondral bone formation, whereas a related molecule BMP12/GDF7 induces connective tissue similar to tendon. Similarly, BMP4 can induce cell death in the hindbrain neural crest, while the related protein dorsalin does not.
Since different BMP family members can induce different fates, then BMP antagonists that have specificity in blocking subsets of BMPs could change the balance of BMPs that are presented to a cell, thus altering cell fate. In view of the importance of relative BMP expression in human health and disease, regulators of cellular function and BMP function in particular, such as noggin and cerberus, provide valuable reagents with a host of clinical and biotechnological applications. The present invention relates to a new family of regulators of cellular function.
Relevant Literature
Bouwmeester, T., et al. (1996) Nature 382: 595-601 describe cloning of the Xenopus cerberus gene and provide a deduced amino acid sequence of Xenopus cerberus protein in addition to describing its biological activity. Lamb, T. M., et al. (1993) Science 262: 713-718; Smith, W. C., et al. (1992) Cell 70: 829-840; Smith, W. C., et al. (1993) Nature 361: 547-549; and Zimmerman, L. B., et al. (1996) Cell 86: 599-606 describe the isolation and function of the noggin protein. Piccolo, S., et al. (1996) Cell 86: 589-598, Sasai, Y., et al. (1995) Nature 376: 333-336, and Sasai, Y., et al. (1994) Cell 79: 779-790 relate to the chordin protein. Enomoto et al. (1994) Oncogene 9: 2785-2791 and Ozaki, et al. (1996) Jpn. J. Cancer Res. 87: 58-61 describe human and murine homologs of the DAN gene.
The invention provides methods and compositions relating to human cerberus protein and related nucleic acids. Included are proteins comprising a human cerberus domain and having human cerberus-specific activity. The proteins may be produced recombinantly from transformed host cells with the subject nucleic acids. The invention provides binding agents such as specific antibodies, and methods of making and using the subject compositions in diagnosis (e.g., genetic hybridization screens for human cerberus transcripts), therapy (e.g., gene therapy to modulate human cerberus gene expression) and in the biopharmaceutical industry (e.g., reagents for screening chemical libraries for lead pharmacological agents).
Preferred uses for the subject human cerberus proteins include modifying the physiology of a cell comprising an extracellular surface by contacting the cell or medium surrounding the cell with an exogenous human cerberus protein under conditions whereby the added protein specifically interacts with a component of the medium and/or the extracellular surface to effect a change in the physiology of the cell. Also preferred are methods for screening for biologically active agents, which methods involve incubating a human cerberus protein in the presence of an extracellular human cerberus protein-specific binding target and a candidate agent, under conditions whereby, but for the presence of the agent, the protein specifically binds the binding target at a reference affinity; detecting the binding affinity of the protein to the binding target to determine an agent-biased affinity, wherein a difference between the agent-biased affinity and the reference affinity indicates that the agent modulates the binding of the protein to the binding target.